Rust Essential Course – Lesson 2

Lesson 2: Hello, Rust! Your First Program

Writing Your First Rust Program

Let’s jump right in:

1. Open your terminal or use the Rust Playground.

2. Enter this code:

fn main() {
  println!("Hello, Rustaceans!");
}

fn main() {
  println!("Hello, Rustaceans!");
}

Code Breakdown

• fn main() { ... }: Every Rust program starts by running the main function.
• println!("Hello, Rustaceans!");: This prints a message to the screen.
  • The ! means you’re calling a macro (a special kind of function).
  • The text inside the quotes is your message.

Interactive Task 1: Run Your Code

• Run the code above.
• You should see this output:

Hello, Rustaceans!

Hello, Rustaceans!

Making It Your Own

Try changing the text inside the quotes to print your name or any other message:

fn main() {
  println!("Welcome to the world of Rust!");
}

fn main() {
  println!("Welcome to the world of Rust!");
}

Challenge: Print Two Lines Instead of One

Try this:

fn main() {
  println!("Rust makes programming fun!");
  println!("Let's keep learning together!");
}

fn main() {
  println!("Rust makes programming fun!");
  println!("Let's keep learning together!");
}

How Rust Runs Your Program

1. Compile: Turning your code into machine instructions — use rustc your_file.rs if using your terminal.
2. Run: Execute the compiled program to see the output.

(If using the Rust Playground, just hit “Run”.)

Mini-Challenge

Write a Rust program that prints:

Learning Rust is rewarding!
Keep going!

Learning Rust is rewarding!
Keep going!

Hint: Use two println!() statements. You can add a blank line between them by using println!("");.

Solution: https://gist.github.com/rust-play/4c81ad149c9273edeaed5d41ffbebb54

Recap

• You wrote and ran your first Rust program.
• You now understand the main function and how Rust prints output.
• You modified the program and tried a mini-challenge!

Go to Course Structure or Navigate to next blog!